This study expands the understanding of lay attitudes towards, and perceptions of cardiovascular risk by exploring beliefs in the context of a large trial of screening and prevention in a ‘healthy’ population. Participants were members of a healthy population (50-79 years) invited to attend screening for asymptomatic atherosclerosis, some of whom were subsequently invited to participate in a randomised control trial assessing the efficacy of aspirin in preventing cardiovascular events. Attitudes and beliefs varied both between and within groups of participants from different stages and situations from the screening and trial process. Prominent themes included: Screening attendance: Participants discussed their own attitudes often as distinct from those of ‘known’ or ‘general’ others. Salient explanations of barriers included fatalism, optimistic bias, denial and disinterest. Screening experience: An ‘at risk’ result often mismatched expectations, and provoked varying reactions: some participants maintained prior beliefs about personal health and risk, seeking alternative explanations; others reinterpreted their pre-screening beliefs. Preventive medicine: Attitudes and behaviour appeared to contradict: prevention was typically described as “better than cure”, and aspirin emerged as a favoured drug with assumptions of trust, safety, and low perceived risk. Trial Participation: Participants’ accounts revealed a wide range of influences on trial participation. When considering benefits and drawbacks of the trial, attitudes expressed ranged from feelings about personal gain or loss, to altruistic attitudes. The present study demonstrates the ubiquity of low cardiovascular risk perception in members of a general public population, and how this underlay attitudes towards screening and prevention, and participation in a preventive research trial. The asymptomatic nature of atherosclerosis, and lack of awareness of the screening measure emerged as particularly important contributors to low perceived risk, amidst the complex context of personal and situational factors in which people make decisions about their health. The findings have implications for, and can inform, the promotion of preventive health for asymptomatic conditions. Furthermore, the findings about attitudes towards, and understanding of, trial participation have implications for those conducting research trials particularly regarding informed consent.